Metal-to-metal heat exchanger for recreational vehicle

ABSTRACT

A heat exchange unit for circulating vehicle radiator liquid is positioned in a large tank that conducts potable water so that the radiator liquid becomes cooled as the potable water becomes heated. The unit includes a container capable of being mounted to the tank and a conduit inserted in heat exchange relationship within the container. For safety purposes a narrow leakage gap is defined between the container and conduit so that any leakage of radiator liquid from the conduit will automatically flow outwardly of the tank where it will be unable to contaminate the potable water.

v Un ted States Patent 1 3,566,957

'[72] inventor James Earl Bridegum [56] References Cited 12143 GothicAve., Granada Hills, Calif. UNITED STATES PATENTS 91344 pp No. 816,6402,669,435 2/1954 Cord et al. l65/70X [22] Filed Apr. 16, 1969 PrimaryExaminer-Martin P. Schwadron [45] Patented Mar. 2, 1971 AssistantExaminerThe'ophil W. Streule Att0rneyPastoriza & Kelly ABSTRACT: A heatexchange unit for circulating vehicle radiator liquid is positioned in alarge tank that conducts potable water so that the radiator liquidbecomes cooled as the [54] FOR potable water becomes heated. The unitincludes a container 10 Cl 4 D capable of being mounted to the tank anda conduit inserted in arms, rawlng lg heat exchange relationship withinthe container. For safety [52] U.S.Cl 165/70, purposes a narrow leakagegap is defined between the con- 165/142 tainer and conduit so that anyleakage-of radiator liquid from [51] Int. Cl F28f1l/00 the conduit willautomatically flow outwardly of the tank [50] Field of Search 165/70,142 where it will be unable to contaminate the potable water.

MAIN DOMESTIC 25?-/ WATER SUPPLY 26 BATHROOM TANK - PATENTEUMAR 2mm J,22 INVENTOR.

5" JAMES EARL BRIDEGUM 33 W& FIG. 4

ATTORNEYS METAL-TO-METAL HEAT EXCHANGER FOR RECREATIONAL VEHICLE CROSSREFERENCE TO PENDING APPLICATION This application is related to acopending US. Pat. application Ser. No. 746,448 filed Jul. 22, 1968 nowPat. No. 3,521,704, granted Jul. 28, I970 and entitled HEAT EXCHANGERFOR RECREATIONAL VEHICLE.

This invention relates to a heat exchange unit and more specifically toa heat exchange unit for simultaneously heating and cooling differentliquid circulating around and through the unit.

, BACKGROUND OF THE INVENTION I The concept of using the circulatingradiator water of a recreational vehicle as a thermal energy source toheat domestic water is known. Some presently operated motor homes andcampers link togetherthe radiator water circuit and domestic watercircuit so that as the domestic water absorbs heat from the radiatorwater, then the radiator water automatically becomes cooled.

However, when the radiator water and domestic water circuits areintegrated in this manner, a potentially serious health hazard arises.Consumers of the domestic water are constantly exposed to thepossibility of having contaminated radiator water seep or leak into thedomestic water. Thus far it has been impossible to isolate the domesticwater and radiator water circuits and still safely take advantage of theheat exchange relationship.

Variousjresponsible governmental and certifying groups that establishexacting plumbing safety standards routinely refuse to approve presentlyemployed vehicle heat exchange systems because they are inherentlyincapable of providing adequate safety for the consumers health. Onecause tending to promote the leakage of radiator water into the domesticwater is that the customary copper tubing for conducting the radiatorwater gradually erodes and deteriorates upon prolonged exposure toantifreeze solutions and other radiator water additives. When the tubebecomes ruptured, radiator water leaks through the tube and becomesmixed with the domestic water. Safe plumbing practices aimed atguaranteeing wholesome water demand that this type of situation beprevented.

Another drawback of conventional vehicle heat exchange systems incampers for example, is that when the camper is replenishing itsdepleted domestic water supply and an undetected leak has occurred thenthe mixed liquid may backflow into the community water supply. Those whoadminister the plumbing codes are especially vigilant of this dangersource and disapprove such proposed vehicle heat exchange systemsOtherwise the serious deficiencies might eventually harm numerouspeople.

BRIEF SUMMARY OF THE INVENTION Briefly described the present inventioncomprehends acompact, inexpensive heat exchange unit that has no movingparts and can be easily assembled, for example, to a recreationalvehicle tank that conducts potable water.

The heat exchange unit includes a metal container with a closed end andan open end, and a metal conduit having an inlet port for admitting aliquid and an exit port for discharging the liquid. The conduit ispositioned in heat exchange relationship within the container and aclosed conduit end is arranged adjacent a closed container end. Aleakage gap is defined between the container inner wall and conduitouter wall in order to conduct any liquid outwardly of the containerthat leaks from the conduit into the leakage gap. The escape through theleakage gap of liquid, which may be vehicle radiator water, prevents theliquid from mingling with and contaminating potable water in the tank.

Preferably the leakage gap clearance between the container inner walland conduit outer wall is between 0.002 inches and 0.005 inches. A flowtube extends through one of the conduit ports and into the interiorportion of the conduit in order to increase the circulation path of therelatively hot radiator liquid through the conduit so that the heattransfer capacity between the conduit and container can be improved.

Preferably the flow tube extends into the conduit by a distanceequivalent over percent of the end-to-end length of the conduit. Amounting flange is joined to the conduit so that the heat exchange unitcan be mounted to the tank.

BRIEF DESCRIPTION OF THE DRAWINGS The numerous benefits and uniqueaspects of the present invention will be fully understood when thefollowing detailed description is studied in conjunction with thedrawings in which:

FIG. 1 is a schematic view showing a vehicle radiator circuitinterconnected by way of the heat exchanger of the present inventionwith a typical recreational vehicle plumbing system;

FIG. 2 is a perspectivepartially sectional view showing the conduitcomponent partially inserted into the container component of the heatexchange unit;

FIG. 3 is a longitudinal cross-sectional view of the container andconduit components fully assembled; and

FIG. 4 is a schematic view showing the simultaneous flow of vehicleradiator water through the heat exchange unit and potable water throughthe tank.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT- Referring to FIG. 1,there is shown a fire wall 10 or other support partition incorporated ina recreational vehicle such as a motor home, camper or pleasureboat. Thevehicle includes a customary engine block 11 and radiator 12 that may befilled withwater and various chemical compounds such as antifreeze notfit for human consumption when a radiator cap 13 is removed. Aconventional fan 14 is mounted to the forward wall of engine block 11. Asupply hose 15 conducts radiator water into a manifold within engineblock 11 and a return hose 16 returns heated water from block 11 toradiator 12.

A flow line for circulating radiator water includes a radiator exit flowline 17 having sections that may be disconnected by an intermediatecoupling'l8, and, a radiator inlet flow line 19 having a similarintermediate coupling 20 for disconnecting segments ofline 19. Lines 17and 19 are arranged to circulate radiator liquid through a portion of aheat exchange system 21. Heat exchange system 21 includes a tank 22which mounts a heat exchange unit 23 coupled to a mounting member 24.

Heat exchange system 21, as shall be fully explained interconnects theradiator water circuit with the vehicle plumbing circuit which conductsdomestic or potable water suitable for cleansing and human consumption.Potable water from a main supply domestic water tank 25 is channeled bya pump or compressor 26 through a main flow line 27. Extending from mainflow line 27 is a first cold water branchline 28 leading to a bathroom29 and a second cold water branch line 30 leading to a sink 31 which maybe located in the vehicle kitchen, bathroom or any other convenientlocation. Potable water flowing downstream of line 30 may be dischargedthrough a drain valve 32 or through a flow line 33 to tank 22. Extendingfrom the top part of tank 22 is a tank exit flow line 34 for supplyingheated water to a riser 35. From riser 35 heated water may be suppliedto sink 31 through line 36 and/or bathroom 29 through another line 37.

FIG. 2 illustrates important details of heat exchange unit 23 which isconstructed of two main components. A metal container 38 is of tubularshape and has an open end 39 and'a closed end 40. Open end 39 is joinedto a mounting flange 41 formed with a series of mounting openings 42 canbe used to mount heat exchange unit 23 to a tank, such as tank 22shownin FIG. 1.

i and 47 areflow tubes 48 and 49 respectively. When conduit 43.is fullyslid into container 38 and heat exchange unit 23 is in operation thenradiator water may flow inwardly through flow tube48, as indicated bydirectional arrow 50, and outwardly through flow tube 49, as indicatedby directional arrow IG. 3 shows heat exchange unit 23 fully assembledand ready for use. Conduit closed end 44 is arranged adjacent containerclosed end.40 and conduit closed end 45 is arranged adjacent containeropen end 39. Container 38 and conduit 43 are relatively sized so thatthe interior wall of container 38 and exterior wall of conduit 43 arepositioned in heat exchange relationship and define a leakage gap 52.Both conduit 43 and v 38 are constructed of metal with outstanding heattransfer characteristics such as copper, aluminum or brass.

The width of leakage gap 52 is sufficiently small so that the heattransfer capacity and efficiency between container 38 and conduit 43 isadequate and is sufficiently large so that the leakage of any liquidsuch as contaminated vehicle radiator water from conduit 43 must entergap52 and then pass outwardly of unit 23. The aim is to preventcontaminated or offensive liquid circulating through conduit 43 frommixing with potable water surrounding container 38. The width of leakagegap 52,.which is sufficiently small for heat transfer purposes andsufficiently large to permit the leakage or escape of offensive liquidis between 0.002 inches and 0.005 inches.

Flow tube 49 is coupled in fluid communication with port 47 and does notextend into conduit 43. In comparison flow tube 48 extends through port46 and has an extension 53 that projects into the interior of conduit43. The purpose of extending only one flow tube into the interior ofconduit 43 is to increase the circulation path of liquid flowing throughconduit 43. in order to increase the overall heat transfer capacitybetween conduit 43 and container 38.

The length of extension 53 is preferably between 85 percent and 97percent of the end-to-end length of conduit 43. By this arrangement agreater quantity of thermal energy has an opportunity to be transferredacross the metalto-metal interface defined by container 38 and conduit43.

If extension 53 were eliminated then, it will be appreciated, a sharpheat transfer gradient would result across the end-toend length of themetal-to-metal interface between conduit 43 and container 38. Maximumheat transfer would occur adjacent conduit outer end 45 and the heattransfer efficiency would gradually diminish to a minimum heat transfervalue adjacent conduit inner end 44. The use of extension 53 causes moreheat to be liberated from liquid circulating through conduit 38 toliquid surrounding container 38. It should be noted that the liquidcirculating through heat-exchanger 23 may be either hotter or colderthan the liquid surrounding heat exchange unit 23, and, liquid may enterflow tube 49 and exit through flow tube 48 or vice versa. I

Referring now to FlG. 4, tank 22 has a space which together with tankinlet line 33 and tank exit line 34 constitutes a part of the maindomestic flow line 27 shown in FIG. 1.

Heat exchange unit 23 is mounted by its flange 41 and bolts to a wall oftank 22. Installed on one side of tank 22 is a gas water heater 54 whichmay be operated to heat the potable liquid circulating through tank 22when the vehicle engine is not running. Heater 54 which-may be aconventional propane heater includes the usual controls 55, main gassupply tube 56,

pilot gas tube 57 and thermocouple 58 for sensing the- OPERATION Keepingthe above construction in mind it can be understood how manydisadvantages of conventional vehicle heat exchange systems are overcomeor substantially eliminated by the present invention.

In order to prepare heat exchange unit 23 for actual use in its intendedenvironment, metal conduit 43 is slid into metal container 38, mountingflange 41 is fixed to an appropriate wall portion of tank 22, and, thenflow tubes 48 and 49 are coupled to different flow segments of theradiator water circuit as indicated in FIG. 1.

When the recreational vehicle motor is running circulating radiatorwater passes through flow tube 49, (referring to FIG. 4), travelsapproximately the end-to-end length of metal conduit 43, reverses itspath and travels through extension 53, and, eventually exits throughflow tube 48. As the radiator water progresses through heat exchangeunit 23 thermal energy is liberated by the radiator water and isabsorbed by the domestic water passing through tank 22. Domestic waterenters tank 22 through flow line 33, and, after circulating around heatexchange unit 23, departs through exitflow line 34. As the domesticwater acquires thermal energy from the radiator water, due to themetal-to-metal contact between container 38 and conduit 43, the radiatorwater automatically becomes cooled in order to improve the operatingefficiency of the vehicle engine.

If intense pressure, metal deterioration, inherent defects or the likecause an inner wall portion of conduit 43 to rupture and develop aleakage passage then, in accordance with safety aspects of thisinvention, the risk of toxic radiator water contaminating the domesticwater is prevented. Radiator water flows into the narrow leakage gap 52and, due to the radiator water pressure, is driven through leakage gap52 outwardly of heat exchange unit 23. The vehicle driver will benotified of the leakage condition by a conventional vehicle dashboardgauge that is responsive to engine overheating or reduced pressure.

From the foregoing it will be evident that the present invention hasprovided a metal-to-metal heat exchange unit for recreational vehiclesin which all of the various advantages are fully realized.

I claim:

1. A vehicle heat exchange system for simultaneously heating potableliquid from a potable liquid source and cooling radiator watercirculating through the vehicle radiator circuit, the system comprising:

a. a tank having inlet and exit lines for admitting and dischargingpotable liquid;

b. a metal container mounted to and projecting into the tank, thecontainer being arranged in heat exchange relationship with the tank;

0. a vehicle radiator flow line segment;

d. a metal conduit coupled to the radiator vehicle flow line segment andhaving an inlet port for admitting radiator water and an exit port fordischarging radiator water, the conduit being positioned within thecontainer and in metal-to-metal heat exchange relationship therewiththroughout the major portion of its length; and

e. means defining a leakage gap between the container and conduit forconducting any radiator water that might leak from a portion of theconduit position within a container to a location outwardly of thecontainer.

2. The structure according to claim 1, wherein; the average clearancebetween the container inner wall and conduit outer wall is between 0.002inches and 0.005 inches.

3. The structure according to claim 1, including; a flow tube extendingthrough one conduit port and into the interior of the conduit, the flowtube being arranged to increase the circulation path of radiator waterthrough the conduit in order to increase the heat transfer capacitybetween the conduit and container.

port.

6. The structure according to claim 1, wherein:

the container has a closed end and an open end for receiving theconduit; and

the conduit has a closed end arranged adjacent the container closed endand a second end that forms the fluid inlet and exit ports.

7. The structure according to claim 6, wherein:

the container is of tubular cross section;

a mounting flange is joined to the container open end;

the conduit is of tubular cross section and has a length substantiallyequivalent with that of the container, and

the leakage gap is of annular configuration. I

8. A vehicle heat exchange system for simultaneously heating potableliquid from a potable liquid source and cooling radiator watercirculating through the vehicle radiator circuit, the system comprising:

a. a tank having inlet and exit lines for admitting and dischargingpotable liquid;

b. a metal container having a closed end and an open end, the containerbeing mounted to and projecting'into the tank and arranged in heatexchange relationship with the tank;

c. a vehicle radiator flow line segment;

(1. a metal conduit coupled to the radiatorvehicle flow line segment andhaving an inlet port for admitting radiator water and an exit port fordischarging radiator water, the conduit being positioned within thecontainer and in metal-to-metal heat exchange relationship therewiththroughout the major portion of its length;

. a flow tube extending through one conduit port and into the interiorof the conduit, the flow tube being arranged to increase the circulationpath of radiator water through the conduit in order to increase the heattransfer capacity between the conduit and container; and

f. means defining a leakage gap between the container and conduit forconducting any radiator water that might leak from a portion of theconduit positioned within the container to a location outwardly of thecontainer, the average width of the leakage gap being between 0.002inches and 0.005 inches.

9. The structure according to claim 8, wherein; the flow l tube extendsover percent of the end-to-end distance of the conduit.

10. The structure according to claim 9, including:

a tank for conducting potable liquid, the metal container being mountedto the tank so that the major portion of the conduit projects into thetank and the leakage gap terminates outwardly of the tank; and

wherein, when relatively high vehicle radiator water is circulatedthrough the conduit and relatively cool potable is circulated throughthe tank the heat exchange relationship between the conduit andcontainer simultaneously causes the potable water to become heated whilethe radiator liquid becomes cooled.

2. The structure according to claim 1, wherein; the average clearancebetween the container inner wall and conduit outer wall is between 0.002inches and 0.005 inches.
 3. The structure according to claim 1,including; a flow tube extending through one conduit port and into theinterior of the conduit, the flow tube being arranged to increase thecirculation path of radiator water through the conduit in order toincrease the heat transfer capacity between the conduit and container.4. The structure according to claim 3, wherein; the flow tube extendsover 90 percent of the end-to-end distance of the conduit.
 5. Thestructure according to claim 4, including; a second flow tube coupled influid communication to the other conduit port.
 6. The structureaccording to claim 1, wherein: the container has a closed end and anopen end for receiving the conduit; and the conduit has a closed endarranged adjacent the container closed end and a second end that formsthe fluid inlet and exit ports.
 7. The structure according to claim 6,wherein: the container is of tubular cross section; a mounting flange isjoined to the container open end; the conduit is of tubular crosssection and has a length substantially equivalent with that of thecontainer, and the leakage gap is of annular configuration.
 8. A vehicleheat exchange system for simultaneously heating potable liquid from apotable liquid source and cooling radiator water circulating through thevehicle radiator circuit, the system comprising: a. a tank having inletand exit lines for admitting and discharging potable liquid; b. a metalcontainer having a closed end and an open end, the container beingmounted to and projecting into the tank and arranged in heat exchangerelationship with the tank; c. a vehicle radiator flow line segment; d.a metal conduit coupled to the radiator vehicle flow line segment andhaving an inlet port for admitting radiator water and an exit port fordischarging radiator water, the conduit being positioned within thecontainer and in metal-to-metal heat exchange relationship therewiththroughout the major portion of its length; e. a flow tube extendingthrough one conduit port and into the interior of the conduit, the flowtube being arranged to increase the circulation path of radiator waterthrough the conduit in order to increase the heat transfer capacitybetween the conduit and container; and f. means defining a leakage gapbetween the container and conduit for conducting any radiator water thatmight leak from a portion of the conduit positioned within the containerto a location outwardly of the container, the average width of theleakage gap being between 0.002 inches and 0.005 inches.
 9. Thestructure according to claim 8, wherein; the flow tube extends over 90percent of the end-to-end distance of the conduit.
 10. The structureaccording to claim 9, including: a tank for conducting potable liquid,the metal container being mounted to the tank so that the major portionof the conduit projects into the tank and the leakage gap terminatesoutwardly of the tank; and wherein, when relatively high vehicleradiator water is circulated through the conduit and relatively coolpotable is circulated through the tank the heat exchange relationshipbetween the conduit and container simultaneously causes the potablewater to become heated while the radiator liquid becomes cooled.